As a fan, first I exclusively followed one group, for more than a year. Then I begun to opened up, checked almost any gg out for what I like. Found too many gems, now I'm a conviced multifandom fan. But I tend too closely follow only few groups.
Multi in the sense of listening to other stuff; mostly solo in the case of actually following what artists are up to. Hell, I barely have time to keep up with what Dreamcatcher are doing, I don't stand a chance multi-ing!
To a lesser extent, I do also follow Stray Kids (though in that case I get most updates from my mum ), (G)I-DLE and Twice.